The first two positions (positions "0" and "1") correspond to positions which can be assumed by a standard crown.
The third position (position "-1") is known in multimode watches, in general in watches with a first analog display indicating the time and a second display, often digital using liquid crystals, indicating one or several other watch functions such as a second time or wake-up time, etc. Thus, in operating the push-piece-crown, the desired mode can be actuated. Such push-piece-crowns are fixed to the stem of the movement in a manner such that when the axial or radial position of the push-piece-crown is changed, the stein is axially or radially displaced. In effect, in rest position 0, the push-piece-crown is coupled longitudinally in a rigid manner to the stem and can be drawn out or pushed in. In the drawn-out position (position "1"), the push-piece-crown is also rigidly coupled to the stem in order to transmit angular information to the movement as, for example time setting, by means of such stem.
It is understood that it is indispensable that the push-piece-crown and the stem return into the initial position because if they remain blocked in the pushed-in position or if they do not return exactly to the initial position, the watch remains blocked in the mode which has been activated.
A known possibility for bringing about return of the stem and its push-piece-crown into their initial positions consists in placing a return spring in the head of the push-piece-crown.
However, this design is generally known from simple push-piece-crowns, that is to say, push-piece-crowns having only two positions, the first (which corresponds to the position "0") in which the stem is free and a second position (which corresponds to the position "-1") in which the stem is engaged with the movement permitting time setting for example. Such a push-piece-crown is described in the patent document CH 577 701. Here, the push-piece crown is also provided with a spring, which is of interest for compensating an alignment defect between itself and the movement. Such push-piece-crown does not have the third position (position "-1") and is of a relatively simple design.
When it is desired to increase the assurance of water tightness of the push-piece-crown (watch of high reliability), there can be introduced a larger sealing gasket into the push-piece-crown. However, should one introduce such a gasket or if several such packings are introduced into a design as described hereinbefore, friction between the push-piece-crown and the guide tube is greatly increased and thus the risk is increased that the push-piece-crown not return into its inactive position because of such friction.
The present invention has thus as purpose to overcome such defects while furnishing a push-piece-crown which exhibits the water tightness suitable for watches of high reliability.